I. Field of the Invention:
The present invention relates generally to digital disk storage systems and more particularly to a multiple independently positionable recording-reading head optical or magnetic disk system.
II. Discussion of the Prior Art:
FIG. 1 shows schematically a typical known single head optical disk positioning system. Such a system includes a transducing head 10 which may use focusing means 12 such as a laser, prism or lens. The head 10 is transported across an optical disk 40 typically using a wormscrew drive or belt drive 50 associated with a stepper motor 30. Because there is only one transducing head on such systems, there is no ability to edit, review or output sensor acquired data while simultaneously accepting an input data stream, for example.
While some known devices use multiple transducer heads to access data storage disks, none of the known devices offer the ability of these heads to move and act independently of each other and either read or write data which was read or written by one of the other heads on the same side of such disks. U.S. Pat. No. 4,644,515 to Allebest et al. discloses one example of such a device. Allebest et al. utilizes a substrate-based array of heads such that a disk with 54,000 tracks has 54,000 read heads. It offers and discusses only read access. The device disclosed in Allebest features heads that are not mobile and thus cannot be used with the continuous track recording method wherein the tracks are actually a single track spiraling inward and the radial position of the track varies constantly. The Allebest et al. device cannot achieve truly continuous access to new data since a single track cannot be read by two heads simultaneously. Allebest et al. also faces difficulties in overcoming the technical hurdles required to be overcome for implementing a 54,000 head read mechanism and system support represents an order of magnitude increase in prototyping and low volume production costs. Allebest et al. does not even address write capabilities for such a fixed array system.
FIGS. 4 and 5 are schematic views of prior art disk systems employing single recording-reading heads. As shown in FIG. 4, recording reading head 60 is typically a magnetic transducer mounted on sweep arm 62. The recording-reading head then sweeps across the disk 64, which is typically a magnetic media type disk, through the control of a mechanical control means 66. Mechanical control means 66 is well known in the art and may be, for example, a separate motor or servo motor.
FIG. 5 illustrates schematically another well known transport mechanism for a single-head system. The head 60 is transported by cantilever arm 70 in a radial path traversing the disk tracks. The cantilever arm 70 is typically controlled by a motor 67, such as a stepper motor or equivalent device. As in the optical disk device of FIG. 1, since there is only one transducing head on the system shown in FIGS. 4 and 5, there is no ability to edit, review, or output data from one area of the disk while simultaneously performing other equivalent tasks to information on other areas of the disk media.
In contrast, the present invention discloses a multi-head and drive mechanism system implemented in a technically feasible configuration of existing recording-reading heads and servo hardware.
An excellent application of a high capacity multiple independently positionable read/write head drive would be on almost any advanced autonomous, semi-autonomous or information gathering remote vehicle or platform. Obvious examples include recognizance and deep space satellites or probes and autonomous battlefield robotics. In these very demanding applications, the flexibility of the invention to simultaneously read, write and alter several high bandwidth streams of data simultaneously would be invaluable.
Such applications typically have a high level of imbedded signal processing and analysis capability related to a limitation of transmission capabilities back to their control center. A remotely or autonomously guided surveillance aircraft for example, might acquire high resolution, multispectral sensor and video information but only have the transmission capability equal to a low resolution video signal. If such a vehicle were equipped with the invention discussed herein, no significant data need be lost as this device would allow a heretofore unavailable length of time to analyze, compress, enhance, prioritize or rebroadcast the data.
In one possible situation where real time flight control was required over a target area, the controller could view the low resolution image and then retroactively request specific high resolution data be sent for more detailed analysis. The ability of the drive to input, output and manipulate multiple streams of data without interruption means that even when transmitting selected information back to base, there need be no limitation on the continued collection and signal processing of new data.